The present invention refers to a device for embossing a foil, the device comprising a pair of rollers which are provided with teeth of the same kind and which are coupled to a drive and capable of being driven in common, the rollers being capable of being pressed against each other in a resilient manner, and to a method for the operation of a device for embossing a foil which comprises a pair of rollers having toothings of the same kind which engage in each other in operation. A device of this kind is described in detail in U.S. Pat. No. 5,007,271. This known embossing device was based upon the problem of achieving both a high quality of the embossing and in particular a mutual synchronization of the embossing rollers in spite of the relatively fine teeth of the latter while only one of the rollers is driven and in turn drives the other roller. It had been found that these requirements were difficult to fulfill if the two rollers were equally provided with hardened teeth in order to ensure acceptable lifetimes of the rollers.
In order to fulfill the requirement of the mutual synchronization of the embossing rollers, the rollers were mutually aligned in such a manner that the circumferential rows of teeth of both rollers lie in the same plane, so that the flanks of the teeth in the meshing area of the two rollers contact one another and a forced driving of the idle roller by the driven roller results.
The mentioned disposition resp. the mutual alignment of the embossing rollers has been practical as long as the embossed foils, especially packing foils, were mainly aluminum foils. Recently, however, paper foils are increasingly used or even prescribed. These foils are substantially stiffer than aluminum foils, and it has been found that the known embossing rollers are no longer adapted to the requirements.